We are running alot of 7.3 on in our UIM. Even if it's not supported, all of them are working fine.

Some history and good to know maybe, because alot of people still think the system is called AS400 or iSeries

IBM changed the name of AS400/OS400 to iSeries/i5/OS in 2000. And in 2006 the platform was rebranded again to IBM Systems i. Then again in 2008, the platform was renamed to IBM Power Systems and the OS name became IBM i, and still is today.